I've been listening to Ophelia, an album by Natalie Merchant, and there's a track where she sings with a woman called Karen Peris, who has a strangely childlike voice, very haunting, almost irritating in its sweetness, but pure and true.

Looked up Karen Peris and discovered that she sings with a band called Innocence Mission. Who can tell me more about them? What's their best album, best song?